Dealer didn't want me to keep the tranfer case as it had to go to bmw. They think it would be the worm gear which would be torn down. Unfortunately, I can't say more as I don't know...
Here is the story about what happened to the tc : http://www.e90post.com/forums/showthread.php?t=749059
2008 BMW 335xi MT e90
JB4 G5, WW meth kit, turbonetics intercooler, DCI, UR catted dp's, UR catback, koni yellow + H&R springs, Rieger front bumper, Avant Garde 19" wheels